1. Field of the Invention:
The invention relates generally to a sheet delivery system on a rotary press, and more particularly to a sheet feed system with an apparatus provided underneath the delivered sheet to decelerate the sheet on its trailing end by means of conveyor belts which are guided by drive and deflection rollers, and between which there is a suction chamber beneath the conveyor belt.
2. Description of the Prior Art:
German Laid Open Patent Application No. DE-OS 24 60 504, which corresponds to U.S. Pat. No. 4,030,727, entitled "Sheet Transfer Device for Printing Presses" illustrates an apparatus of this type on which the delivered sheet is braked on its end by conveyor belts for which there is a suction chamber. As a result of the deceleration of the distributed sheet, the distance between it and the following sheet decreases so that, with sheets in close succession and a high machine speed, it is impossible to completely avoid collisions between the leading edge of the subsequent sheet and the trailing edge of the preceding sheet. This leads to a disruption in the distribution of the sheets and possibly to damage of the sheet itself.
German Laid Open Patent Application No. DE-OS 34 12 180 illustrates another embodiment in which there is also deflection rollers with a suction belt. In this case, the deflection rollers with the suction belt are pivoted downward via a pivot so that the sheet can drop down during the deceleration process toward the surface of the stack. The disadvantage of this configuration of the prior art is that the distributed sheet has to be bent in a vicinity of its trailing end to obtain sufficient suction action. With this configuration, therefore, it is not possible to process stiff material, e.g., cardboard, because a bending of the trailing end would not be possible. The end of the sheet would only be in contact with its edge on the suction belts so that no suction action or deceleration of the sheet could be achieved. Another significant disadvantage is that if the deceleration process should begin prematurely by means of the downward tipping of the suction belts, the trailing sheet end would be raised above the delivery level of the successive sheet so that the successive sheet might run into the end of the preceding sheet. It becomes impossible to positively prevent a collision of the two sheets when the ends of the sheets overlap during the deceleration process. Both of the afore-mentioned patents are incorporated by reference as if the entire contents thereof were fully set forth herein.